1. Field of the Invention
The invention relates to a process for determining the density of a loaded drilling fluid from a deep well, in particular an oil well. Additionally, the invention relates to equipment for carrying out this process.
2. Description of the Prior Art
In deep-drilling, the drilling fluid is, inter alia, used for conveying the drillings out of the well. At the same time, however, it also absorbs other materials, for example gases, water or the like, and entrains them up to the surface. The nature and amount of such materials contained in the drilling fluid make it possible to draw certain conclusions, inter alia, on the type of the geological strata which are cut through by the well, and also on possible blow-outs which endanger the well.
It is known to monitor the drilling fluid continuously by determining its specific gravity or its density in order to be able to draw conclusions on the gas content in this way. For this purpose, the pressure of the drilling fluid is determined in a section of the length of a column of drilling fluid at two points which are offset in height, and its temperature is determined between the pressure-measuring points. The specific gravity is obtained by forming a differential pressure value, and this is compensated using the measured temperature (DT-OS 2,507,026). The characteristic of the known process is the determination of the specific gravity of the drilling fluid in absolute values so that the measured pressures must be compensated using a measured temperature value. Thus, in addition to the gas content, other influences on the density of the drilling fluid also enter into the measurement. These include waters from the strata, slurries of different drillings or the like. Since, frequently, it is precisely the gas content which matters, and other influences are superimposed on the influence of the gas content on the density of the drilling fluid, more accurate information cannot be obtained by the known process.